Starter mechanism for thread rolling machine



March 5, 1968 E. G. GROHOSKI ET AL STARTER MECHANISM FOR THREAD ROLLING MACHINE 2 Sheets-Sheet 1 Filed Dec. 7, 1966 INVENTORS EDWARD G. GROHOSKI ROBERT D MORTON WWW? ATTORNEYS E. G. GROHOSKI ET AL 3,371,820

March 5, 1968 STARTER MECHANISM FOR THREAD ROLLING MACHINE Filed Dec. '7, 1966 2 Sheets-Sheet 2 EDWARD 3. GROHOSKI ROBERT D. MORTON ATTORNEYS United States Patent Office 3,371,820 Patented Mar. 5, 1968 3,371,820 STARTER MECHANISM FOR THREAD ROLLING MACHINE Edward G. Grohoski, Litchfield, and Robert D. Morton, West Hartford, 'Conn., assignors to The Hartford Special Machinery Company, Simsbury, Conn., a corporation of Connecticut Filed Dec. 7, 1966, Ser. No. 599,786 12 Claims. (Cl. 221-21) The mechanism of this invention has a movable starter blade for successively positioning work blanks in a work station, and a lost motion connection is provided between the starter blade and the drive therefor to automatically discontinue the movement of the starter blade upon occurrence of an abnormal condition.

The present invention pertains to an improved starter mechanism for fastener forming machines such as, e.g., thread rollers.

A principal object of the invention is to provide an improved starter mechanism which is particularly suited to accommodate for example occasional misfeeds of work blanks, resulting in a jammed condition, even at increased speeds of operation.

Another object of the invention is to provide an improved starter mechanism, the operation of which is automatically discontinued immediately upon the occurrence of an obstruction such as a jammed work blank to virtually eliminate premature breakage and other damage to machine parts.

A further object of the invention is to provide an improved starter mechanism having a return mechanism which is independent of a main drive thereof and which is quickly and easily adjusted for effecting a controlled starting force in accordance with the size of the work blanks and a desired speed of operation so as to minimize improper starts.

Still another object of the invention is to provide an improved starter mechanism which is of minimum weight and increased responsiveness for high production operation.

A still further object of the invention is to provide an improved starter mechanism of an overload release type which is capable of being incorporated in either new or existing fastener forming machines.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereafter set forth and the scope of the application which will be indicated in the appended claims.

In the drawings:

FIG. 1 is a plan view, partly broken away and partly in section, of a portion of a thread rolling machine showing a preferred embodiment of a starter mechanism constructed in accordance with this invention, the starter mechanism being shown in an engaged operative condition;

FIG. 2 is an enlarged section View, partly broken away, taken generally along line 22 of FIG. 1;

FIG. 3 is a reduced isometric view showing a pivotable crank incorporated in the starter mechanism of the invention;

FIG. 4 is a reduced isometric view, partly broken away, showing a link of the starter mechanism which cooperates with the pivotable crank of FIG. 3; and

FIG. 5 is a partial plan view, on a reduced scale, showing the starter mechanism of FIG. 1 in a disengaged inoperative condition.

Referring now in detail to the drawings wherein a preferred embodiment of the invention is shown, it will be understood that while the starter mechanism of this invention is susceptible of applications in various apparatus such as pointers, slotters, head trimmers etc., a typical application is in a thread rolling machine as described in our copending United States patent application entitled Starter Mechanism for Thread Rolling Machine, Ser. No. 412,022, filed Nov. 18, 1964, now Patent No. 3,314,261 and assigned to the assignee of the present invention.

A portion of a thread rolling machine is shown in FIG. 1 for illustrative purposes wherein a column of headed work blanks 10 are loaded in an inclined gravity feed chute 12 to be fed between thread rolling faces 14 and 16 of a stationary die 18 and a movable die 20 having a reciprocating drive, not shown, of a type well-known in the art. The blanks 10 are fed one at a time by working end 24 of a reciprocable starter blade 26 of a starter mechanism 28 which is the subject of this invention. As in our referenced patent application, the starter blade 26 provides for gating the feed chute 12 and wedging each blank in succession between the stationary and movable dies 18, 20 in their starting position (as viewed in FIG. 1) in timed relation to the reciprocation of the movable die 20.

A suitable arrangement for actuating the starter mechanism 28 is fully described in our referenced patent application wherein a cam and cam follower arrangement is provided for pacing the operation of a main drive assembly as at 30 having a turnbuckle link such as at 34 secured thereto for reciprocating movement in synchronism with the movable die 20. However, other actuating means could be provided for retracting the turnbuckle link 34 to the left of its position shown in FIG. 1, such as the pneumatic cylinder 35 illustrated in part in the preferred embodiment.

Heretofore, return movement of a drive member such as the turnbuckle link 34 has normally been utilized in conventional fastener forming machines to return the starter blade 26 in a feeding direction, e.g., for wedging a blank 10 between the dies 18, 20 after the blank is positioned on the working face 16 of the movable die 20 by retraction of the starter blade 26. As described in our referenced patent application, return movement of the turnbuckle link 34 toward the work station is provided by a drive return device 36 of the main drive assembly 30 which must normally effect a substantial force sufiicient to return the main drive assembly 30 from a retracted position to its position illustrated in FIG. 1 and maintain the main drive assembly 30 therein throughout each operating cycle of the machine. However, when it is desired to significantly increase the machine production rate such that each operating cycle of the machine is typically in the order of 150 milliseconds (0.150 second), e.g., the force required of the drive return device 36 has been found to be dangerously excessive when applied to the starter blade 26, resulting in the starter blade 26 being forced into the path of the movable die 20 and causing considerable damage to the parts concerned, inducing improper starts and misfeeds, and even damaging the work blanks, particularly when they are of small size or formed of relatively soft material such as aluminum.

In accordance with the present invention, the starter blade 26 is essentially isolated from the drive return device 36 of the main drive assembly 30 and is returned by independent means under a minimal driving force from a retracted position into its blank feeding position illustrated in FIG. 1.

More specifically, a one-way drive crank is mounted on a stationary pivot shaft 52 fixed relative to a stationary frame or machine'table 53 and includes a first pair of lugs 54 between which is mounted a cam roll 55 secured by means of a fastener 56. The cam roll 55 is engaged by a contoured end portion 58 of plunger 60 which is part of the drive return device 36.

Plunger 60 thus continuously urges the drive crank 50 in a counterclockwise direction as viewed in FIG. 1 under the biasing force of a pair of axially aligned compression springs 64, 66. Spring 64 has a lower spring rate than spring 66 and surrounds a sleeve 67 slidably mounted on plunger 60. The length of sleeve 67 is suitably dimensioned to effect a preselected limited compression of spring 64.

Thus in biasing the clockwise rotation of drive crank 50, the two springs 64, 66 compress in amounts proportional to their spring rates until sleeve 67 stops further compression of spring 64 upon sleeve 67 contacting washers 68 and 70 against which are also seated the opposite ends of the lighter spring 64. Further clockwise movement is absonbed entirely by spring 66. A proper choice of springs 64 and 66, together with the length of sleeve 67, is made to provide a varying biasing force sufiicient to return the main drive assembly 30 from a retracted position in a counterclockwise direction to its position illustrated in FIG. 1.

As stated above, the spring 64 has its opposite ends seated against opposed faces of a pair of washers 68, 70 slidably mounted on plunger 60 in spaced apart relation. Spring 66 has one end seated on an opposite face of washer 70, and the other end of spring 66 is seated inside a plug 72 threadably secured in an apertured block 74 fixed to a mounting bracket 76 screw mounted to the machine table 53. It will be understood that the plug 72 has an axial Opening extending through a rearwardly projecting hex head 78 for accommodating axial movement of plunger 60.

The drive crank 50 includes an additional pair of lugs 82 angularly offset from lugs 54 and attached to turnbuckle link 34 by a suitable connector 84, and the hex head 78 of the drive return device 36 may be readily adjusted by means of a wrench, not shown, for precisely varying the spring force exerted on the drive crank 50 to rotate the same in a counterclockwise direction in accordance with an amount required for effecting return movement from left to right of the turnbuckle link 34 via the drive crank 50.

The starter blade 26 is suitably attached to an elongated bracket 86 carrying a pair of upstanding pivot pins 88, 90, and the starter blade 26 and its bracket 86 are supported for substantially straight-line reciprocating movement as set forth in our referenced patent application, by starter blade linkage mounted for swinging movement about the pivot shaft 52 and a second pivot shaft 92, both of which are fixed relative to the mounting bracket 76.

The starter blade linkage includes a rear lever 94 (FIG. 4) positioned to the left as viewed in FIG. 1 behind drive crank 50, linking pivot pin 88 to pivot shaft 52, and an L-shaped forward lever 96 having an arm portion 98 generally parallel to, but longer than rear lever 94 for linking pivot pin 90 to pivot shaft 92.

For continuously biasing the above described starter blade linkage towardits blank feeding position as shown in FIG. 1, the forward lever 96 additionally includes a second arm portion 100 angularly displaced from the first arm portion 98 and having a pair of ears 102, 104 secured by a fastener 106 to an independent return mechanism 110. The latter includes parts similar to those of the above described drive return device 36, and the same numerals followed by the latter a have been used to identify like parts.

Referring now more particularly to FIGS. 2-4, the drive crank 50 and the rear lever 94 of the starter blade linkage each have a pair of generally cylindrical, coaxially aligned knuckles, respectively shown at 112, 114 and 116, 118 integrally formed in spaced relationship to interfit with one another for retaining the assembly in pivotal connection upon being fitted onto the pivot shaft 52. To provide minimal inertia, the above described components of the starter blade linkage are preferably formed of a suitable lightweight material such as aluminum, and a starter blade linkage of improved responsiveness is effected by the provision of suitable bearing sleeves such as at 120, 121, 122, 123, and 124 for eliminating sliding contact between the complementary interfitting knuckles of the drive crank 50 and the rear lever 94. For restraining axial displacement of the starter blade linkage, a top plate 125 is fixed to a block 127 secured in turn to the mounting bracket 76, and set screws 126, 128 are shown securing the pivot shaft 52, 92 against rotation relative to the top plate 125. In addition, the rear lever 94 in the preferred embodiment is illustrated as having a mortised cutout 129 so that a hardened metal block 130 can be inset and secured thereto by an suitable means such as by screw 131 with an outer face 134 of the block 130 positioned for abutting engagement with an impact face 136 formed on a projection 138 of the drive crank 50.

By virtue of the above described construction, the drive crank 50 will be seen to be in positive driving relation to the rear lever 94 in only one direction for effecting a retracting movement of the starter blade 26 upon operation of the main drive assembly 30. Springs 64a, 66a of the return mechanism 110 may be of preselected size for providing a minimal biasing force of significantly lower value than that provided by springs 64, 66.

In addition, the biasing force of return mechanism 110 is quickly and easily varied by rotating the hex head 78a of the plug 72a to a properly adjusted position, as described above in connection with the drive return device 36, thereby to readily provide an adjusted spring force which will be sufficient to overcome the inertia of the starter blade linkage and to effect a starting force which produces a following motion of rear lever 94 in a blank feeding direction in response to a return movement of the drive crank 50, but insufficient to initiate movement of the starter blade 26 and its linkage upon the occurrence of an abnormal condition such as in the case of a jammed blank obstructing normal feeding of the machine as depicted in FIG. 5. It will now be apparent that when the starter blade 26 is disabled, the drive crank 50 will continue to operate under the influence of the main drive assembly.

It will be understood that suitable means, not shown and not essential to the invention, may be readily incorporated to shut off the starter mechanism and to close off the feed track 12 so that in the event of a misfeed, the machine may be readily cleared to resume operation.

A fastener forming machine incorporating the present invention thus is readily operated to effect a normal feeding operation in the absence of an abnormal feed; is effective in minimizing improper starts and misfeeds; and virtually eliminates the danger of damaging the work blanks of various operating parts of the machine in high speed production operations. In view of the disclosed lost motion connection between the starter blade linkage and the main drive therefor, the only force exerted on the starter blade is that effected by the independent return mechanism of the starter blade linkage which is readily adjusted for effecting a proper return force in accordance with a preselected size of the work blanks and a desired speed of operation.

As will be apparent to persons skilled in the art, various modifications and adaptations of the structure above described will become readily apparent without departure from the spirit and scope of the invention, the scope of which is defined in the appended claims.

We claim:

1. In a thread rolling machine of the type having a starter mechanism including a movable starter blade for high speed feeding of a series of work blanks from a feed chute to a work station, a linkage supporting the starter blade for movement toward and away from the work station, and drive means including a drive return device for pacing the operation of the starter blade linkage, the improvement comprising a pivotable crank responsive to operation of the drive means and its drive return device, and biasing means continuously urging the starter blade linkage into direct engagement with said pivotable crank for effecting a resilient lost motion connection between the drive means and the linkage upon occurrence of an abnormal feeding condition.

2. The improvement as recited in claim 1 wherein said biasing means comprises a spring connected to the starter blade linkage for maintaining the same in direct following engagement with said pivotable crank when the same is operated under the force of the drive return device, for exerting a starting force on the starter blade in the absence of an abnormal feeding condition.

3. The improvement as recited in claim 1 wherein said pivotable crank is movable under the force of the drive means in one angular direction for simultaneously moving the starter blade linkage away from the Work station, and wherein said pivotable crank is movable under the force of the drive return device in the opposite angular direction independently of the starter blade linkage to eifect an overload release through said resilient lost mo tion connection upon occurrence of an abnormal feeding condition.

4. The improvement as recited in claim 1 wherein said biasing means is adjustable to establish a preselected force urging the starter blade toward the work station.

5. The improvement as recited in claim 1 wherein said biasing means comprises a return spring for applying to the starter blade linkage a biasing force of an amount insufiicient to move the starter blade in the event of an abnormal feeding condition but sufiicient to urge it toward the work station in the absence of an abnormal feedding condition so that the linkage follows the return motion of said pivotable crank toward the work station.

6. The improvement as recited in claim 2 wherein said spring is connected to the starter blade linkage independently of said pivotable crank and the drive means, said spring being adjustable for effecting a preselected starting force on the starter blade linkage and which starting force is isolated from the force of the drive return device.

7. The improvement as recited in claim 3 wherein said pivotable crank is mounted for angular movement about a pivotal axis coinciding with that of a link of the starter blade linkage for abutting nonsliding engagement therewith.

8. The improvement as recited in claim 5 wherein said pivotable crank is continuously operable in response to the drive means and its return drive device when move- 6 ment of the starter blade is discontinued in the event of an abnormal feeding condition.

9. A starter mechanism usable in a thread rolling machine for high speed feeding of a series of work blanks from a feed chute to a work station and comprising a stationary frame, a movable starter blade, a linkage mounted on said frame'and connected to said starter blade for supporting the same for movement, a one-way drive crank mounted for pivotal movement on said frame for moving said linkage solely in one angular direction away from the work station, and a spring connected directly to said linkage continuously urging it in the opposite angular direction toward the work station for maintaining said linkage in direct engagement with said drive crank, said spring being adjustable to apply to said linkage a preselected spring force sufiicient to cause it to follow said drive crank in said opposite angular direction for moving said linkage toward the work station in the absence of an abnormal feed but insuflicient to initiate movement of said linkage upon the occurrence of an abnormal feed.

10. The starter mechanism of claim 9 further including first and second pivots secured to said frame, said linkage having first and second links of different length mounted on said first and second pivots and connected to said starter blade for supporting the same for substantially straight line reciprocating movement.

11. The starter mechanism of claim 9 further including drive means connected to said drive crank for operating the same, said drive means having; biasing means directly connected to said drive crank continuously urging it in said opposite angular direction for pivotal movement independently of said linkage.

12. The starter mechanism of claim 10 wherein said drive crank is pivotally mounted on said first pivot, and wherein said spring is operatively connected to said second link and continuously urges said first link into direct engagement with said drive crank in said opposite angular direction for eifecting a resilient lost motion connection between said drive crank and said linkage upon occurrence of an abnormal feeding condition.

References Cited UNITED STATES PATENTS STANLEY H. TOLLBERG, Primary Examiner. 

1. IN A THREAD ROLLING MACHINE OF THE TYPE HAVING A STARTER MECHANISM INCLUDING A MOVABLE STARTER BLADE FOR HIGH SPEED FEEDING OF A SERIES OF WORK BLANKS FROM A FEED CHUTE TO A WORK STATION, A LINKAGE SUPPORTING THE STARTER BLADE FOR MOVEMENT TOWARD AND AWAY FROM THE WORK STATION, AND DRIVE MEANS INCLUDING A DRIVE RETURN DEVICE FOR PACING THE OPERATION OF THE STARTER BLADE LINKAGE, THE IMPROVEMENT COMPRISING A PIVOTABLE CRANK RESPONSIVE TO OPERATION OF THE DRIVE MEANS AND ITS DRIVE RETURN DEVICE, AND BIASING MEANS CONTINUOUSLY URGING THE STARTER BLADE LINKAGE INTO DIRECT ENGAGEMENT WITH SAID PIVOTABLE CRANK FOR EFFECTING A RESILIENT LOST MOTION CONNECTION BETWEEN THE DRIVE MEANS AND THE LINKAGE UPON OCCURRENCE OF AN ABNORMAL FEEDING CONDITION. 